Question about ZoneAlarm's KHOBE Response

I read ZoneAlarm's KHOBE response this afternoon and attempted to follow the steps as outlined. On my Vista 32-bit laptop, it worked with no problem. But on my Vista 64-bit desktop, the "Enable Timing Attack Prevention" option is greyed-out and couldn't be checked.

Is this because this whole thing is just an issue on 32-bit systems? Just curious and wanted to make sure it was supposed to be greyed-out on 64-bit OS.